Die



H. ROSENBERG July 4, 1939.

' DIE v Origiqal Filed Jan. 14, 19 33 3 Sheets-Sheet 1 1' July 4, 1939.

H. ROSENBERG Original Filed Jan. 14. 1953 :5 Sheets- Sheet 2 3mm HEYMANRIJS ENBERB,

July 4, 1939.

FI G- 7.

a. manna III HBYM N ROSENBERG;

Patented July 4, 1939 UNITED STA ES PATENT OFFICE 651,783. 1933, SerialNo. 674,087

24 Claims.

Previously known and used parts and operations are hereinafter mentionedas standard practice to differentiate from the present inven- It iscommon in standard practice to roll threads and other ribs on fastenerssuch as wood screws and drive pins, but it has not been possibleheretofore to roll a thread or other rib with an interruption or spacebetween alined or otherwise disposed sections of the-rib.

Also, it is standard practice to make rib-rolling dies by milling with astandard universal milling machine, and steel blocks thus milled toprovide a die face are afterward hardened to enable the die face in eachinstance to stand up under the strain of thread or other rib rolling;but it is not feasible to produce by such milling operation a die facehaving obstructions in the rib-forming grooves of the die, and, ofcourse, it is not possible to provide by such milling, operationobstructions of different widths and heights or with abrupt ends; and itis further not feasible to roll a longitudinal rib of no pitch or ofrelatively high pitch on a fastener blank except by insuring suchgripping action between the blank and die as to insure rotation of theblank with the relative movement of one die with respect to the other,and such gripping action is in standard practice assured by providingnicks in the ridges between ribforming grooves in the dies, and ofcourse by makingthe initial grooves full length, that is as long as thefinished rib is to be. If an interruption or fill should be provided inthe initial grooves, the resulting reduction in gripping ac-- tion ofthe dies against the fastener blank would tend to cause slipping andfailure of the blank to roll with the stroke of the movable die, and if'the fill were of sufllcient size such failure would surely occur.

One of the essential objects of the present invention is the forming ofa die adapted for the rolling of a fastener and thereby forming thereona rib, such as a thread or the like, outstanding from the body andhaving an interruption in its length, and in greaterdetail a furtherobject is the production of such a die for forming .on a fastener body aplurality of such ribs each with an interruption, and in still greaterdetail a still further object is production of such a die for theforming of such interruptions with the interruptions of one ribstaggered relative to those'of another.

A more specific and detailed object is the successful and commercialrolling of fasteners such for instance as disclosed in my Patent No.

not, the cost of production Divided and this application June 2,

1,686,468, dated October 2, shown in my Patent No. 1,545,471, dated July7,

While the inventions of my said patents were conceived and practiced byme prior to the respective filing dates of the applications on which thepatents issued, such practice was accomplished through hand operations,and though the fasteners of the said patents proved themselves ofunusual merit in use both in metal and in wood, and of great valuewhether hardened or by other means than rolling proved substantiallyprohibitive; that is to say, the fasteners produced otherwise than byrolling were so expensive as to cause consumers to prefer less eflicientsubstitutes at less cost.

The use of the die of the present invention overcomes the difficultiesto the rolling of the type of fastener referred to, and enables itsproduction by a rolling process carried out in the operations of astandard thread-rolling machine.

Numerous, expensive, and carefully conducted tests from the time of myproduction of the invention of my said Patent No. 1,545,471, to the timeof the production of the present invention havedemonstrated that therolling of such a fastener as shown in my said patent was previouslyutterly impossible, and this fact is generally known and recognized inthe industry, but this impossibility is overcome by the presentinvention.

With the above indicated and other objects in view, as will in parthereinafter become apparent and in part be stated, the inventioncomprises a die for rolling fasteners having rib-forming grooves and anobstruction in one of the grooves.

The invention further comprises such a die in which a series ofobstructions are arranged successively in a series of grooves, and theinvention, still further comprises such a die in which such obstructionsare graduated in size until some of the grooves are filled at the placesof the obstructions.

The invention still further comprises astandard-milling-operation-produced die for rolling a ribbed fastenerand having an obstruction intermediate the ends of one of therib-forming grooves.

The invention also comprises, in a die, certain other novelconstructions, combinations, and arrangements of parts as subsequentlyspecified and claimed.

In the accompanying drawings:

- Figure 1 is a detailed, fragmentary perspective of one of thelaminations of the initial die de- 1928, and also such as tached, theview being a magnification of the customary or normal size of laminationfor clearness of disclosure.

Figure 2 is a top plan of the completed initial or laminated die, theparts being shown in a reduced scale relative to Figure 1, but stillsubstantially enlarged with respect to the ordinary, commercial die.

Figure 3 is a view similar to Figure 2 of the back face of the sameparts, the parts being shown on a scale substantially that of normal,commercial working size.

Figure 4 is a diagrammatic showing of the formation of a hob from. thedie seen in Figure 2.

Figure 5 is a top plan view of a hob or negative of a die embodying theface formation of the parts seen in Figure 2.

Figure 6 is a view similar to Figure 4 showing the formation of a soliddie from the hob.

Figure 7 is a face plan view of the die formed as indicated in Figure 6,and corresponding in enlarged showing to that of Figures 2 and 5.

Figure 8 is an enlarged, fragmentary perspective view of the dischargeend of the stationary laminated die.

Figures 9 and 10 are elevations of fasteners made in accordance with thepresent invention. Figure his a detailed, fragmentary section takendiagonally of that part of the die having the reduced obstructions orflat portions leading toward the completed interruption-formingobstructions or flat portions, the section being taken approximately online |lll of Figure 7.

It will be observed that the fasteners seen in Figures 9 and 10correspond substantially to the fastener seen in my Patent-No.1,545,471. except that the structure seen in Figure 10 is ribbed orthreaded to the tapering portion of the entering end, and it is obvious.of course, that the ribs or threads might extend to the very enteringtip where such a construction is found desirable; whereas the structureseen in Figure 9 is provided with a pilot characterized by being ofsufficiently greater length than the pilot shown in my said patent toinsure the formation of a cylindrical burr from a sheet of metal. asdistinuished from a mere flared or bell-shaped burr.

Referring to Figures 9 and 10 in detail, I indicates the body of afastener which is shown as having a head 2 of the type commonly employedfor engaging sheet metal. such as galvanized iron sheeting, but, ofcourse. the fastener body I may have any desired shape of head or nohead at all. Outstanding from and extending in the general direction ofthe length of the body are ribs or threads I. I, interrupted at l. andso arranged that the uninterrupted portions of the threads or ribsoverlap andare thusstag ered with relation to the interruptions ofadjacent threads or ribs. An advantage of this sta gered relationshipresides in the fact that. when the fastener is driven into wood or othersupporting material, the ends of the thread sections afford a betteranchorage by virtue of engaging spaced and dlflerent parts of thesupporting material. Withdrawing are greatly resisted by the fact thatthe ends of the thread sections. and

particularly the outer or upper or last entering ends thereof at theplaces of the interruptions. are abrupt or squared on so as to presentabrupt shoulders to overlying material which has sprung into the path ofsuch shoulders, if the material be wood or the like. or has flowed intosuch path if the material be metal, such as soft iron or soft steel.when the fastener is to be used in metal,

the ribs or threads 3 are preferably hardened, as by a case-hardeningprocess, so that the said ribs or threads will be sufiiciently hard toenter metal, such as soft iron or soft steel substantially withoutinjury to such ribs or threads. The hardening operation may be that ofthe well known cyanide case-hardening, or any other, appropriate ordesirable tempering may be utilized.

The body I is preferably provided with rounded surfaces so as to besubstantially cylindrical throughout the places where the threads orribs do not appear, and thus to be rounded and cylindrical.between andlaterally of the thread or rib sections as well as in the spaces ofinterruption of such threads or ribs.

The entering end portion of the body I may assume any desired shape orcontour, but is preferably pointed for facility of entry either in thefinding of an opening in metal, or the easy entry into wood or the like.A pilot 5 may be provided when and as desired, according to the use towhich the fastener is to be put. The pilot results from using fastenerblanks of greater length than the width of the dies and properlylocating the blanks in engaging the dies.

It should be borne in mind that the fastener such as seen in Figure 9,is formed with the ribs or threads rolled in place from the material ofthe original blank body, and that the term rib is utilized 'to includean outstanding ridge similar to a thread whether possessed of pitch ormerely parallel to the longitudinal axis of the fastener body, while theterm thread is intended to include some degree of pitch, variation inwhich may occur to any desired extent, as, for example,

if a wood screw type of fastener is to be provided with interruptions inthe thread. the pitch will be much lower than that seen in Figure 9, andthe pitch shown in Figure 9 is indicated as preferable where thefastener is to be hammer-driven or otherwise inserted by directaxially-delivered force.

Thus. the term rib" is employed as generically descriptive of variousforms of ridges, while the term "thread is spec fic to a ridge havingpitch or inclination about the body of the fastener.

In Figure 10 the fastener I has the head 2',

ribs or threads 3', interrupted at 4', and the entering end portion 5which. as seen, is preferably without the pilot. the structure shown in"Figure 10 being thus substantially identical with that seen in Figure9, except for the absence of the pilot in the former.

It was readily recognized by me when producing the fastener in the firstplace, such as seen in Figure 9, that a die could not be produced forrolling the fastener by the usual milling operation, because of theinterruptions in the die grooves n to produce the interruptions in thethreads or ribs, and the fact that such interruptions must be abrupt,not rounded out, and must be staggered with respect to uninterruptedportions of adjacent ribs created a problem incapable of being overcomeby a mere milling operation on an ordinary die blank.

Without attempting to review the extensive experimentations and eiiortsmade by me to discover a means ofsuccessfully rolling the type offastener illustrated in Figures 9 and 10, and in my above-identifiedpatents, among other things I produced what for the sake of adescriptive term I call a laminated die. In other words, I divided thedie face into as many parts, sections, frag ments, or laminatlons asnecessary to'leave in any one part, section, or lamination only thecharacter of depressions capable of being produced by a millingoperation, with the result that I secured a series of plates orlaminations 6, as-seen in Figure 2, and one of which is seen in enlargeddetail in Figure 1. Each of these laminations is formed with depressionsor V-shaped grooves I, I, and with intervening obstructions or flatportions 8. It should be observed that the grooves 'I need notnecessarily be V-sliaPBd but will have that transverse contourcorresponding to the form of the rib or thread to be rolled,and,'sincethe edge type of rib or thread is illustratively selected andshown in Figures 9 and 10, the V-grooves 'I are necessarily required. Aswill be plain from Figure 2, some of the die fragments or laminations orplates 6 do not have the fiat surfaces 8, such, for example, as the twomarginal laminations of Figure 2, but each of the laminations does haveflat areas 9, 9, between each two of the grooves 'I so that, during therolling operation, the cylindrical form of the body of the fastener willbe maintained cylindrical while material is flowed out into the groovesI, and the flat portions 8 serve to finish off those portions of thebody I cylindrical between the sections of the interrupted thread orrib. Thus, each lamination 6 must have its own peculiar contourtodispose the flat surfaces 8 in the right relation to the groovedportions I not only of the particular lamination, but relative to allthe other laminations making up the entire die, whereby the fiatportions 8 appear scattered and staggered over the face of the dieproperly to register relative to each other and to the final area of theroot diameter or reduced body por tion of the body after the rib orthread sections have been flowed out into place.

It is standard practice for rib rolling purposes, particularly where therib is without pitch or is a high pitch thread, as with a drive screw orpin, that the initial end of each die, that is, the end beginning therolling operation; or first engaging the blank, will have its ridgesbetween grooves nicked or roughened to assure suflicient frictionalengagement to insure rolling of the engaged pin blank or. body.Thispractice is carried out with the present invention, though notillustrated to avoid confusion in the showing.

It isnot practicable and probably not feasible to roll a rib to acompleted condition with interruptions maintained from the first, andtherefore, the grooves I in the initial development, that is at thestarting end of each die, are full length and uninterrupted, so that inoperating, ribs are rolled that are full length initially; but after thedies have gotten the rolling operation well under way, it has been foundby me to be entirely possible to flow away parts of the initial rib toproduce interruptions in its length. It is of course.

best, if not absolutely necessary for nicely finished work, that thissuppression or flowing away of intermediate parts of an alreadydeveloped rib should occur gradually, so that the metal will move eitherover into the retained sections of the rib or back into the body of thefastener smoothly and without too much resistance or causing roughnessof finish.

Accordingly the obstructions or fiat portions 8 are developed in thelength of the die face at a substantial distance from the beginning orinitial end of the die, and the development of these fiat portions 8 isaccomplished'by graduated steps or in gradual manner, by providingobstructions or-flat portions Ill in grooves 'I (see Figures land 11)which start a substantial distance from the initial end of the die asvery low flat portions, and gradually increase in height untilgraduating into the full height flat portions 8. Naturally, fiatportions I widen as they increase in height so as to transversely fillthe respective grooves 'I at the place of their location, so that eachgroove I at each place where a fiat portion Ill exists is of a differentdepth from, that is bf a less depth than, the other portions of thegroove. Each flat portion II] from the very beginning is of a length thesame as a flat portion 8, whereby a straight shoulder is developed foreach flat portion 8, and the ends of the preserved sections of rib atthe interruptions are correspondingly'flat and outstand straight so asto present abrupt shoulders.

Thus, in the actual rolling operation, the ribs or threads as they areformed in the initial end portion of the die, seen at the left hand sideof Figure 2, are actually full length without interruption in theirinitial form, but are first 'slightly interrupted by the first of thereduced obstructions or flat portions l0 and then by the graduation ofsaid reduced portions lo the interruptions are step by step enlarged inwidth and depth to the size of the obstructions or flat portions 8.Thus, each fragment, section, or lamination 6 has its initial grooves Ivaried according to variation to be caused in the flowed rib, wherebycertain parts are flowed out to rib form and then back on being engagedby the flat portions I0 and 8 until certain parts of the initiallyformed threads are restored to the body of the fastener I or flowed intothe retained rib sections.

Naturally, the fragments or pieces or laminations 6 can best beaccurately produced by a carefully-prepared diagram to be followed bothin the forming of the laminations as to thickness and edge contour sothat the edge contour of each coordinates with that of the otherlaminations to be used. When all of the laminations have been completedaccurately, as from following a diagram, they are ready to be assembled.By dividing up the die into such fragments or laminations, the millingoperation can be carried out on an ordinary standard universal millingmachine, and when the several laminations or fragments are ready theyare brought together to correspond with the provisions of the guidingdiagram and are H, II, seen in dotted lines in Figure 3 to produce thecompleted, laminated die I2. Lamina- In actual practice, however, I findthat thislaminated die does not completely solve the problem of rollinginterrupted threads. Those familiar with thread rolling will be familiarwith the fact that in the use of such machines it is customary tocarefully block and clamp in the two cooperating dies which are toproduce the ribbed product. This blockingin and clampingfastenedtogether, as by rivets operation is accomplished with thegreatest available facility for holding the dies as rigid as possibleand allowing no relative movement whatever thereof, since even theslightest movement would destroy the satisfactory condition of thefinished rib, or render the rib defective. However, notwithstanding mostcareful efforts to block and clamp the laminated dies against theslightest movement, the several laminations do actually move relative toeach other under the strain of rolling fasteners, and thus producedefective fasteners of a character undesirable for marketing purposes.

Without detailing the further experiments conducted by me, except to saythat no method of fastening the laminations together satisfactorilyovercame their tendency to and capacity of individual movement, Ieventually found that such a die as seen in Figures 2 and 3 made up oflaminations or fragments secured together while incapable of successfuluse for direct rolling purposes was, under proper conditions, capable ofuse for the forming of a die hob. Die hobs are,

as is known in the art, the negatives of dies, and are customarilyproduced by being pressed against the die face with suificient pressureto cause the metal of the hob to assume the negative contouncoincidingwith the positive contour of the die. Standard practice includes use ofsuch enormous pressure for this work as one hundred tons per squareinch, and even then repeated impressions with interspersed annealing ofthe die being formed are necessary to produce a com,- pleted die facefrom a die hob. Standard practice was followed by me to produce a hobfrom the laminated die after the manner indicated in Figure 4.

When the hob block l3 has its negative die face I completed, the blockis carefully hardened, and then according to standard practice dies l6are made therefrom, asfrom die blocks l5. When the die I6 is completed,the block l5 being integral is free from possibility of any portion ofit giving or moving relative to any other portion thereo The die face I6is, of course, identical with the die face of die I! except that thelamination lines do not exist, and, therefore, the same referencenumerals have been applied to the die It and the same description willapply.

' The drive screw or ribbed fastener produced by the die l6 as seen inFigure 9 (and, of course, Figure 10) is characterized by having a seriesof spiral ribs or threads each of which would be continuous except forthe interruptions l, and

these interruptions are produced by the flat portions 8 and theirpredecessors II of the die Ii. Between each two of these ribs or threadsthe body of the fastener is exposed in the form of the base of thevalley between said ribs or threads, which valley is indicated on Figure9 at la, la, the said valleys la being formed by the flat face portions4b of the die It. It should, of course, be understood that an importantfeature of the die construction is its capacity not only to produce theinterruptions l in each of the several ribs or threads, but to producethem in their staggered relation with respect to adjacent ribs orthreads such that wherever an interruption 4 appears the two threads orribs arranged adiacent to the interrupted thread are not interrupted'inthe length of the fastener for the length of the particular interruption4. Thus, any cross section taken through a fastener at a place where aninterruption I occurs will show the two adjacent ribs '3 in crosssectionand the rib where the interruption 4 occurs in end view. crosssection through the fastener taken near one-of the interruptions I willshow the three ribs or threads in cross section incident to the fact ofthe staggering and overlapping of the retained sections of ribs.

As will be readily recognized by those familiar with the art, thelaminated die seen in Figure 2 is the reciprocating one when consideredin its relationship to the thread-rolling machine, and the stationarydie, considered with respect to the thread-rolling machine, will beidentically the same in contour and manner of construction except that,as seen in Figure 8, the discharge end of the laminated die is roundedoff, as at H, as by being filed off before hardening, so that thestationary, completed die corresponding to the die It, has its dischargeend rounded off, so that the discharging fasteners will not have theirribs or threads injured by being forced across an abrupt angle.

Each of the rib-forming grooves l of the completed die would be acontinuous groove extending from one edge of the die to the other butfor the fact that it is interrupted at several places by webs orungrooved portions of the die body which divide the groove into spacedsections, and each web or ungrooved portion that produces a divisionprovides ends to.each section with the walls of the ends presentingabrupt clearlydefined angles to the walls or sides of the respectivegroove sections. Thus the completed die in operating on a pin-like blankand rotating the blank about its axis (as is common practice in therolling of screws and like threaded fasteners) first develops the threadribs and then depresses sections of the ribs to leave outstanding ribsections having their ends in the form of faces at clearly defined andabrupt angles to the sides faces of the respective rib, all as is clearfrom the product obtainable from the die as seen in Figures 9 and 10 ofthe drawings.

This application is a division of my co-pending application Serial No.651,783, filed January 14, 1933, for improvements in the Art of forminginterrupted-rib fasteners.

What is claimed is:

1. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having a milled rib-forming groove divided into spacedsections, and an intermediate ungrooved portion of the die face in theline of and between the groove sections, presenting an abrupt wall at aclearly defined angle to the sides or walls of the groove.

2. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having a milled rib-forming groove divided into spacedsections, and an intermediate ungrooved portion of the die face in theline of and between the groove sections, the groove sections meeting theungrooved portion in abrupt shoulders.

3. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having a milled rib-forming groove with a part of thegroove of a different depth from another part thereof, and the wallprovided by the less depth part being flat andclearly defined at anangle to the confluent walls of those portions of the groove of greaterdepth.

4. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having a rib-forming groove with a part of the groove ofa different depth from another part thereof, and the different depths ofthe groove meeting in an abrupt shoulder, and the wall provided by theless depth part being flat and clearly defined at an angle to theconfluent walls of the portions of the groove of greater depth. I

5. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having a rib-forming groove divided into spaced sectionsand an intermediate ungrooved portion of the die face in the line of andbetween the sections, and the ungrooved portion having flat facesclearly defined at an angle to and meeting the faces of the respectivegroove sections, and the die face also having a rib-forming groove witha part of the groove of a different depth from another part.

6. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having a rib-forming groove divided into spacedsections, and an intermediate ungrooved portion of the die face in theline of and between the groove sections, the groove sections meeting theungrooved portion in abrupt shoulders, and the ungrooved portion havingfiat faces clearly defined at an angle to and meeting the faces of therespective groove sections, and the die face also having a rib-forminggroove with a part of the groove of a different depth from another partthereof, and the different depths of the groove meeting in an abrupthoulder.

'7. A die as claimed in claim 5 wherein the die face is provided with aseries of such grooves made up of spaced groove sections and interposedungrooved portions, and the die face is also provided with a series ofthe grooves having different depths, and the die face is also providedwith a series of full length full depth rib-forming grooves.

8. A die as claimed in claim 5 wherein the die face is provided with aseries of the grooves made up of spaced groove sections and interposedun grooved portions, and the die face is also provided with a series ofthe grooves having different depths, and the shallower portion of oneofthe grooves having different depths varying in depth with respect tothe shallower portion of another of the grooves having different depths.

9. A die as claimed in claim 5 wherein the die face is provided with aseries of the grooves made up of spaced groove sections and interposedungrooved portions, and the die face is also provided with a series ofthe grooves having different depths, and the shallower portions of thegrooves having different depths varying in depth with respect to eachother and graduating in shallowness toward the grooves formed of spacedsections.

10. A die as claimed in claim 5 wherein the die,

face is provided with a series of the grooves made up of spaced groovesections and interposed ungrooved portions, and the die face is alsoprovided with a series of the grooves having different depths, and theshallower portions, of the grooves having different depths varying indepth with .respect to each other and graduating in shallowness towardthe grooves formed of spaced sections, the shallower portions beingstaggered in the length of the die.

11. A die for forming interrupted-rib fasteners comprising adie bodywith a die face having a series of milled rib-forming grooves eachdivided into spaced sections with ungrooved portions of the die faceinterposed between the groove sections, and said interposed ungroovedportions being staggered'in the length of the die each ungrooved portionhaving a flat face clearly defined at an angle to and meeting the facesof the respective grooved portion.

12. A die for forming interrupted-rib fasteners comprising a' die bodywith a die face having a series of milled rib-forming grooves eachdivided shallo-wer portions of the grooves the die sections presentgrooves of into spaced sections with ungrooved portions of the die faceinterposed between the groove sections, and said interposed ungroovedportions beingstaggered in the length of the die, the die face beingalso provided with a series of rib-forming grooves of different depthsat different places, the shallower depths of the last-mentioned groovesbeing staggered in the length of the die to correspond with thestaggering of the ungrooved portions between the sections of thefirst-mentioned grooves.

13. A die for forming interrupted-rib fasteners comprising a die bodywith a die face having ribforming grooves each divided into spacedsections,

and an intermediate ungrooved portion of the die face in the line of andbetween the groove sections, and the die face also having rib-forminggrooves each with a part of the groove of a different depth from anotherpartthereoL-and the die face further having full length grooves ofuniform depth, and the full length grooves being located at thebeginning end portion of the die, followed by the grooves havingdifferent depths, and the latter followed by the grooves formed ofgroove sections spaced with alined ungrooved portions therebetween.

14. A die as claimed in claim 13 wherein the shallower portions of thegrooves of different depths are alined in the length of the die tocooperate with the ungrooved portions between the sections of thefirst-mentioned grooves.

15. A die:as claimed in claim 13 wherein the of different depths arealined in the length of the die to cooperate' with the ungroovedportions between the sections of the first-mentioned grooves, and thesaid shallower portions being graduated in depth a complete die faceembodying configurations exceeding capacity for production by standardmilling operations and including groove sections having flat side facesabruptly meeting fiat terminal faces at clearly defined angles and eachof said die sections having its portion of a die face limited toconfigurations such as a flat side face or faces of a groove or groovesor a flat end face or faces thereof with the oonfigurationorconfigurations of each die section limited to being within the capacityfor production by standard milling operations.

1'7. A die as claimed in claim 16 wherein some of the die sectionspresent ungrooved portions lying across grooves of other of the diesections.

18. A die as claimed in claim 16 wherein some of different depths fromgrooves of other sections with which they aline.

19. An integral die body having a die face developed on the die claimedin claim 16.

20. A die comprising fragments assembled to provide a die face, certainof the fragments having milled depressions or grooves forming parts ofthe die face, and other of the fragments having ungrooved portionsforming parts of the die face and blockading some of the depressions,the ungrooved or blockading portions presenting flat faces abruptly andat clearly defined angles to the confluent faces of the grooves.

21. A die as claimed in claim 3 wherein the die face has another milledrib-forming groove paralleling the first and with a part of a diflerentdepth from another part and of a diflerent depth from thefirst-mentioned part of the first-mentioned groove.

22. A die for rolling interrupted-rib fasteners of the type ofscrew-threaded fasteners comprising a die body or block of metal and adie face on said block having rib-forming grooves with material of theblock disposed in the line of and intermediate the ends of the groovesto provide interruptions in the length of the grooves, each of theinterruptions being such as to preclude a continuous milling cutterstroke in the production of the respective groove, and each interruptionpresenting faces clearly defined and abruptly at angles to the faces ofthe interrupted portions of the grooves.

23. A die as claimed in claim 22 wherein the material interrupting someof the grooves is sufficient in quantity to only partially fill thegrooves and partially interrupt them, and wherein such quantity isgraduated in the length of the die to the places where the interruptionsof the grooves are complete.

24. A die as claimed in claim 22 wherein the material of the blockdisposed in the line of and interrupting the grooves extends from theplane of the base of the grooves upward toward the face of the die.

HEYMAN ROSENBERG.

